The present invention relates to piezoelectric sounding components and manufacturing methods thereof.
In conventional electronic equipment, such as cellular phones and household appliances, piezoelectric sounding components that produce warning sounds and operation sounds, such as piezoelectric speakers and piezoelectric sounders, are in wide use.
For example, Japanese Unexamined Patent Application Publication No. 2004-15767 discloses such a piezoelectric sounding component. The piezoelectric sounding component described in the foregoing published application has a structure where a piezoelectric sounding body (diaphragm) constituted of a piezoelectric element, which is ceramic for example, and a metal plate, is accommodated in a casing.
In the foregoing piezoelectric sounding component, a piezoelectric element is coated with a coating agent, such as polyimide-based resin or epoxy-based resin. The metal plate is bonded to the casing with an elastic sealant such as a urethane-based sealant or a silicone-based sealant.
However, when different materials are used for the coating agent and the sealant, films having different moduli of elasticity are formed on a surface of a diaphragm. Consequently, distortion of vibration may occur in a boundary between the coating agent and the sealant in the diaphragm and problems in terms of reliability, such as separation on an interface between the coating agent and the sealant, may occur.
The present invention has been made in view of such circumstances and one of the objects of the invention is to provide a piezoelectric sounding component with a favorable vibration characteristics and reliability.